1. 首先备份

/etc/yum.repos.d/CentOS-Base.repo

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2. 进入yum源配置文件所在文件夹

[root@localhost yum.repos.d]# cd /etc/yum.repos.d/